How Much Does a Custom Client Portal Cost to Build in 2026?

The verdict in three sentences

In 2026, a custom client portal costs between 18,000 and 35,000 EUR for a simple version (invoices, documents, tickets) and 45,000 to 90,000 EUR with billing, SSO and online payment. Add 60 to 250 EUR/month of EU hosting and 12 to 18 % of the build per year in maintenance. Against a SaaS module billed at 49 to 199 EUR per user per month, custom becomes cheaper once you pass 30 active users.

What each price tier covers

Portal pricing depends first on functional scope. A read-only space (the client views documents) is nothing like a transactional portal (the client pays, signs, opens tickets). Here are 2026 orders of magnitude at a French day rate of 500-650 EUR.

The gap between 35,000 and 90,000 EUR comes from three items: authentication (a real SAML/OIDC SSO is 5-12 dev days), billing/payment (Stripe or GoCardless integration, reconciliation, dunning: 8-20 days) and access control (who sees what, per role and per organization: 6-15 days).

The hidden costs over 3 years

The build quote is only the visible part. Total cost of ownership (TCO) includes hosting, maintenance and evolutions. A well-designed portal pays off over 3 to 4 years.

For a portal built at 50,000 EUR, expect 7,500 to 9,000 EUR/year of maintenance, i.e. a 3-year TCO around 75,000 to 82,000 EUR including hosting.

Custom vs SaaS module: the real math

A SaaS client-portal module costs 49 to 199 EUR per user per month. With few users, SaaS wins. But the bill scales linearly, whereas custom is a fixed, amortized cost.

The tipping point sits around 30 active users. Beyond it, each extra user is nearly free in custom, while it costs 99 EUR/month in SaaS.

Mini case study

Claire, CFO of an industrial SME in Lyon (85 staff, 220 B2B clients), was drowning in email requests for invoices and delivery notes. She was eyeing a SaaS at 129 EUR per user/month for her 45 internal and client users, i.e. 69,660 EUR over 3 years. Kolonell proposes a custom portal at 48,000 EUR, with invoices, documents and tickets, plus 7,200 EUR/year of maintenance. Three-year TCO: 69,600 EUR - even with SaaS from year one, but with an owned, extensible asset. Above all she saves 6 hours/week of manual handling, roughly 12,000 EUR/year of admin time.

FAQ

How long to deliver a custom client portal? Count 8 to 16 weeks depending on tier. A simple portal ships in 8-10 weeks; an advanced portal with SSO and payment needs 12-16 weeks, including testing and a security audit.

Is custom really cheaper than SaaS? Yes, from 30 active users. Below that, SaaS at 49-199 EUR/user/month stays cheaper; above it, the fixed cost of custom (build + maintenance) becomes clearly advantageous over 3 years.

Where is the data hosted? At Kolonell, on EU infrastructure (OVH or Scaleway) for 60 to 250 EUR/month, GDPR-compliant, with encrypted backups and access logs. Non-EU hosting is avoided for personal data.

What maintenance budget should I plan? Maintenance of 12 to 18 % of the build per year, i.e. 6,000 to 9,000 EUR/year for a 50,000 EUR portal. It covers fixes, version upgrades and a buffer of minor evolutions.

Can the portal connect to our ERP or billing tool? Yes. An ERP (Sage, Cegid, Odoo) or billing integration adds 8-20 dev days, i.e. 4,000 to 13,000 EUR depending on API complexity and data volume to sync.

Let's scope your project. Tell us your client count, the documents to expose and your payment/SSO needs: we'll frame a portal at the right tier, with an indicative budget between 18,000 and 90,000 EUR. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.